1. Field of the Invention
The present invention relates to a multi-stage system for treating hazardous wastes such as oil well drilling waste material, wherein a high efficiency multi-stage incinerator includes a rotary kiln stage fired by a venturi shrouded burner having controlled inflow of burner fuel and air flow, with an upstanding generally vertical scrubbers that is fired at its lower end by one or more secondary burners, and with vertically spaced water sprayers and cone shaped annular baffles treating the gases produced from combustion with a high surface area of dispersed water droplets.
2. General Background
Rotary kilns and incinerators have been commercially available and used in the treatment of various types of waste including municipal waste, industrial waste, and hazardous waste. Hazardous waste is often contained in open pits or pools. These pits can contain oil, oil drilling wastes, and complex mixtures of hazardous material such as refining refuse and/or plural refinery chemical discharges.
In order to "treat" these open pit hazardous waste products, simple burning has been used in the past. Open pit burning is a highly inefficient and undesirable method of disposing of hazardous waste in pits because of the fact that incomplete combustion scatters soot over a large area, polluting the surrounding area. The settling soot creates a further pollution problem for ground water.
In order to completely decompose hazardous waste, municipal waste, and industrial waste, a high temperature, highly efficient combustion can be utilized. The gaseous discharge of this combustion can be scrubbed so that the gaseous output does not contain polluted or hazardous particulate material or gaseous material which might be an additional source of pollution even after combustion of the initial hazardous waste product. A problem often encountered with the treatment of hazardous waste is that it must be able to handle high product loading rates. Open pits can contain thousands of barrels of waste material that must be incinerated quickly.
Various patents have issued relating to various rotary kiln constructions. Indeed, rotary kilns per se are commercially available. An example of a rotary kiln can be seen in the recently issued U.S. Pat. No. 4,730,564 entitled "Multi-Staged Kiln" issued to Harry Abboud. The Abboud patent discloses a multi-stage rotary kiln for burning waste, suitably skid mounted for easier transport. The kiln includes a pair of concentric tubes affixed one inside the other and rotatable, a first large diameter tube and a second tube of small diameter provided at one end with circumferential wall openings mounted inside the first large diameter tube. An annular passageway between the two tubes is provided and an opening through the second small diameter tube provides a continuous flow path for introducing waste and the hot burning gases. The hot gases flowing concurrently with the waste via the annular passageway and the circumferential openings into and through the second tube. The feed mechanism introduces waste into the annular passageway and an elevator lifts the burning waste from the annular passageway and passes the same into the circumferential openings and the burning waste is transported through the smaller tube and discharged.
Other patents that relate generally to the incineration of waste material using rotary kiln can be seen in the Angelo U.S. Pat. No. 4,734,166 entitled "Furnace For the Selective Incineration Or Carbonization Of Waste Materials"; the Reed et al., U.S. Pat. No. 4,724,777 entitled "Apparatus For Combustion of Diverse Materials And Heat Utilization"; the Bolle U.S. Pat. No. 3,882,801 entitled "Incinerator For Domestic And Industrial Solid, Semi-Liquid Or Liquid Waste"; and the Jaronko U.S. Pat. Nos. 3,906,874 and 3,938,450 entitled "Mobile Furnace Vehicle".
The concept of using a scrubber to treat the gaseous discharge of incineration is disclosed generally in several patents including for example the Marchand U.S. Pat. No. 4,704,972 entitled "Method And Apparatus For Reducing Acid Pollutants In Smoke"; Warner U.S. Pat. No. 4,557,202 entitled "Exhaust Gas Treatment Method And Apparatus"; the Caffyn et al U.S. Pat. No. 4,424,755, entitled "Incineration System Having Cyclonic Oxidation Chamber"; the Celis U.S. Pat. No. 4,392,875 entitled "Smog Eliminator"; the YaGuchi et al U.S. Pat. No. 4,269,806 entitled "Scrubber For Removal of Sulphur Dioxide From Exhaust Gas"; the Spitz U.S. Pat. No. 4,162,654 entitled "Pollution Control Incineration System", the Hartman U.S. Pat. No. 4,168,958 entitled "Smokestack Air Washer", the Morales U.S. Pat. No. 4,149,901 entitled "Pollution Control And Convection Heater", the Menigat et al U.S. Pat. No. 3,921,543 entitled "Method Of Incinerating Salt Containing Liquid Sludge", the Crawley U.S. Pat. No. 3,823,531 entitled "Gas Cleaner", the Torrence U.S. Pat. No. 3,762,858 entitled "High Temperature Scrap Cleaning Conveyor", the Smuck U.S. Pat. No. 3,701,237 entitled "Smoke Eluminator", the Snelling U.S. Pat. No. 3,646,897 entitled "Method and Apparatus for Pollution Free Burning of Automobile Bodies"; the McClure U.S. Pat. No. 3,533,608 entitled "Smog Arrester", the Bowman U.S. Pat. No. 3,530,806 entitled "Incinerator", the Tomany et al U.S. Pat. No. 3,520,649 entitled "System of Removal of Sulphur Oxide and Fly Ash From Power Plant Flue Gases", the Ford U.S. Pat. No. 3,395,656 entitled "Fly Ash Removal Device For Incinerators", the Frankland U.S. Pat. No. 2,978,998 entitled "Incinerator", the Otto U.S. Pat. No. 2,771,281 entitled "Benzol Scrubbing Method and Apparatus"; the Kameya U.S. Pat. No. 2,709,580 entitled "Smoke Washer"; and the Durant U.S. Pat. No. 999,213 entitled "Apparatus For Bringing a Gas Into Contact With A Liquid".
In the Kameya '580 patent there is disclosed a smokestack of preferably cylindrical shape having dished, annular plates disposed one above the other supported by struts. A hollow spray head of substantially hemispherical shape is mounted on the upper convex side of one of the plates and centrally of the plate with a plurality of spray nozzles projecting radially from the spray head at equal angular intervals therein and are directed toward the outer edge of one of the plates for directing sprays of water over the outer edges of the plates and causing the water to flow downwardly over the outer edges of a successfully lower plates and over the outer edge of the bottom into the bottom annular trough.
Applicant herein is the named inventor of a prior U.S. Pat. No. 3,807,932 directed to a burner construction that incorporates a burning head mounted within a venturi shape shroud. Atomizing is accomplished using fluid that is mixed with the burner fuel.
The present invention provides an improvement over these prior art patents by disclosing a new, improved combination that includes the use of first and second burners positioned respectively at the intake of the rotary kiln and at the bottom of the scrubber portion adjacent the discharge from the rotary kiln. Each of the burners is preferably of an atomizing type, having a burning head mounted internally of a venturi shaped shroud, the burner receiving controlled flow of both air and liquid fuel such as low cost diesel fuel so that the flow of fuel for burning and the flow of air through the venturi can be controlled at both the primary and at the secondary burners to produce a highly efficient burn. Particulate matter leaving the bottom end portion of the scrubber stack is cleansed of any minute or particulate material that might not be completely burned during combustion.